A valve timing control apparatus is used for an internal combustion engine such as a vehicle engine to adjust opening and closing timing of a valve for achieving a suitable operating state of the internal combustion engine. The valve timing is controlled by displacing a relative rotation phase between a driving rotation member, which is synchronously rotated with the crankshaft, and a driven rotation member which is synchronously rotated with the camshaft.
An advance angle chamber and a retard angle chamber are formed between the driving rotation member and the driven rotation member. When the hydraulic fluid is supplied to the advance angle chamber, the rotation phase of the driven rotation member relative to the driving rotation member is displaced in an advance angle direction. When the hydraulic fluid is supplied to the retard angle chamber, the rotation phase is displaced in a retard angle direction. A partition such as a vane, provided at the driven rotation member, separates the advance angle chamber from the retard angle chamber.
In the valve timing control apparatus disclosed in JP H11-182216A, a groove is provided between an outer surface of the partition and an inner surface of the driving rotation member. A sliding contact portion between the outer surface of the partition and the inner surface of the driving rotation member is sealed due to the presence of the hydraulic fluid in the groove. Consequently, leaking of the hydraulic fluid, caused by a pressure difference between the advance angle chamber and the retard angle chamber, is prevented.
In the valve closing and opening timing apparatus disclosed in JP H11-182216A, when the oil pressure of the hydraulic fluid is high in one of fluid pressure chambers, i.e. the advance angle chamber or the retard angle chamber, the pressure of the hydraulic fluid, entering the sliding contact portion, becomes higher, compared to that of a normal case. When the hydraulic fluid enters the sliding contact portion, if the hydraulic fluid enters from the fluid pressure chamber to the groove filled with the hydraulic fluid, the hydraulic fluid overflows from the groove. As a result, the hydraulic fluid may leak to the other fluid pressure chamber, or the hydraulic fluid may leak to an exterior of the valve timing control apparatus through a communication hole into which a camshaft is inserted.
In the case, the oil pressure is not maintained at a proper level in the advance angle chamber or the retard angle chamber, and the performance deteriorates. For example, the response speed of the valve timing control apparatus slows down.
A need exists for a valve timing control apparatus which is not susceptible to the drawback mentioned above.